Practice Exam #3 Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The energy of a photon of light is __________ proportional to its frequency and __________ 1) proportional to its wavelength. A) directly, inversely B) directly, directly C) indirectly, not D) inversely, inversely E) inversely, directly 2) What color of visible light has the longest wavelength __________ ? 2) A) violet B) green C) yellow D) red E) blue 3) Of the following transitions in the Bohr hydrogen atom, the __________ transition results in the 3) emission of the highest-energy photon. A) n = 1 → n = 6 B) n = 3 → n = 6 C) n = 6 → n = 3 D) n = 1 → n = 4 E) n = 6 → n = 1 4) The __________ subshell contains only one orbital. 4) A) 6f B) 4s C) 1p D) 3d E) 5d 5) The ground state electron configuration for Zn is __________. 5) A) [Ar]4s23d10 B) [Kr]3s23d10 C) [Kr]4s23d10 D) [Ar]4s13d10 E) [Ar]3s23d10 6) All of the __________ have a valence shell electron configuration ns1. 6) A) noble gases B) alkali metals C) chalcogens D) halogens E) alkaline earth metals 7) Elements in the modern version of the periodic table are arranged in order of increasing 7) __________. A) oxidation number B) average atomic mass C) number of isotopes D) atomic mass E) atomic number 1 8) In general, as you go across a period in the periodic table from left to right: 8) (1) the atomic radius __________; (2) the electron affinity becomes __________ negative; and (3) the first ionization energy __________. A) decreases, increasingly, increases B) decreases, increasingly, decreases C) increases, increasingly, decreases D) decreases, decreasingly, increases E) increases, increasingly, increases 9) The __________ have the lowest ionization energy. 9) A) alkali metals B) chalcogens C) transition metals D) halogens E) alkaline earth metals 10) In the Lewis symbol for a fluorine atom, there are __________ paired and __________ unpaired 10) electrons. A) 4,1 B) 6, 1 C) 4, 2 D) 0, 5 E) 2, 5 11) Based on the octet rule, phosphorus most likely forms a __________ ion. 11) A) P3+ B) P+ C) P5+ D) P5- E) P3- 12) The only noble gas without eight valence electrons is __________. 12) A) Ne B) Ar C) He D) Kr E) All noble gases have eight valence electrons. 13) Which of the following would have to lose two electrons in order to achieve a noble gas electron 13) configuration __________? O Sr Na Se Br A) Na B) Sr, O, Se C) Sr D) O, Se E) Br 14) A double bond consists of __________ pairs of electrons shared between two atoms. 14) A) 1 B) 2 C) 3 D) 4 E) 6 15) A polar bond will form between two __________ atoms of __________ electronegativity. 15) A) different, opposite B) identical, different C) similar, different D) identical, equal E) different, different 2 16) The formal charge on carbon in the molecule below is __________. 16) A) +1 B) +2 C) +3 D) -1 E) 0 17) According to VSEPR theory, if there are four electron domains in the valence shell of an atom, they 17) will be arranged in a(n) __________ geometry. A) trigonal planar B) octahedral C) trigonal bipyramidal D) linear E) tetrahedral 18) The molecular geometry of the CS2 molecule is __________. 18) A) tetrahedral B) linear C) T-shaped D) bent E) trigonal planar 19) According to valence bond theory, which orbitals on hydrogen atoms overlap in the formation of 19) the bond in H2? A) 1s B) 1p C) 2s D) 2p E) 3d 20) The hybridization of orbitals on the central atom in a molecule is sp2. The electron-domain 20) geometry about this central atom is __________. A) trigonal planar B) tetrahedral C) linear D) octahedral E) trigonal bipyramidal 21) In order to produce sp3 hybrid orbitals, __________ s atomic orbital(s) and __________ p atomic 21) orbital(s) must be mixed. A) one, three B) two, two C) two, three D) one, two E) one, one 22) There are __________ σ and __________ π bonds in the H2CCCH2 molecule. 22) A) 6, 4 B) 4, 2 C) 2, 2 D) 2, 6 E) 6, 2 3 23) There is/are __________ π bond(s) in the molecule below. 23) A) 0 B) 1 C) 2 D) 4 E) 16 SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 24) (3 pts) What is the energy (J) of a green photon of light that has wavelength of 532 nm? 24) (h = 6.626 x 10-34 J s) 25) (3 pts) Explain the main observation about the H-emission spectrum and what new theory 25) concerning the structure of the atom is inspired. 26) (2 pts) What is the condensed electronic configuration aluminum (Al) and indicate how 26) many core electrons it has and how many valence electrons it has. 27) (3 pts) Why does effective nuclear charge increase from left to right on the periodic table? 27) 28) (2 pts) (Circle the right choice) Halogens are very reactive because they ARE / ARE NOT 28) very electronegative. 29) (3 pts) Briefly describe the characteristics of a covalent bond 29) 30) (9 pts) Draw the Lewis structure for C2F4, CO, and SO3 (draw all resonance structures, if 30) any). For each compound indicate the total number of electons and the formal charge of each atom. 31) (5 pts) How many electron domains are there in CHCl3? what will the shape be? Is it polar 31) or nonpolar? 32) (5 pts) How many electron domains are there in N3- ? what will the shape be? Is it polar 32) or nonpolar? 33) (2 pts) Describe the location of the electrons in a pi bond with respect to the nuclei. 33) 34) (8 pts) Draw a picture of the resulting orbitals when an 's' orbital hybridizes with a 'p' 34) orbital. How many hybrid orbitals are produced? What is the 3-D shape that these orbitals have? What is the name of this hybridization? 35) (3 pts) Explain how nonbonding electrons influence the shape of molecules. 35) 4 Answer Key Testname: PRACTICE TEST 3 1) A 2) D 3) E 4) B 5) A 6) B 7) E 8) A 9) A 10) B 11) E 12) C 13) C 14) B 15) E 16) E 17) E 18) B 19) A 20) A 21) A 22) E 23) C 24) 3.74 x 10-19 J 25) The colors that were emitted were in discrete lines, not a continuum. This led to the conclusion that electrons were in quantized orbits around the nucleus and that light absorbed or emitted corresponded to distinct jumps between these energy levels. This was the Bohr model of the atom. 26) Al : [Ne] 3s2 3p1 10 core electrons and 3 valence 27) Because the atomic number (Z) increases but the number of shielding electrons (S) stays the same. Since Zeff = Z - S, if Z increases and S is the same, then Zeff will increase. 28) ARE 29) A covalent bond occurs between two atoms when they share electrons. Electrons in half full obitals will overlap to complete their octet and act a 'glue' to hold the nuclei together. 30) C2F4 has 36 e-, all atoms have a formal charge of 0. CO has 10 e-, the formal charges are: C = -1 and O = +1 SO3 has 24 e-, the formal charges are: S = +2, O = 0, O = -1, and O = -1. 31) 4 domains, tetrahedral, polar 32) 2 domains, linear, nonpolar 33) The bonding electrons in above and below the nuclei. 34) 2 orbitals are produced. The hybridization is an 'sp' hybrid. 35) Nonbonding electrons take up more space than bonding electrons and act to compress the bond angles of the other electron domains. 5.